Aerofoil blades, such as fan blades for ducted fan gas turbine engines and propellers for turboprop gas turbine engines are conventionally either of a solid or composite structure.
A solid structure, typically of metal, is advantageous in terms of blade integrity and cost, but is not conducive with weight reduction and consequent improvements to operating efficiency.
It is also known to provide lighter, composite blades that have both solid metallic portions and foamed metallic portions. Whilst these have a certain integrity to impact from foreign debris ingested by the engine, the blades of the prior art still lack robustness.